Translation guide
The English phrase "first part" can refer to the initial section of something, the opening segment of a performance, or the first installment of a series. Japanese uses different words depending on what is being divided.
Referring to the beginning portion of a book, movie, speech, event, etc.
The first half or earlier part of something. Commonly used for time periods, events, or structured content.
映画の前半は少し退屈だった。
The first part of the movie was a little boring.
試合の前半は互角だった。
The first part of the match was evenly matched.
Literally 'the initial part'. A straightforward, neutral phrase that works in many contexts.
レポートの最初の部分を書き直した。
I rewrote the first part of the report.
The very beginning or opening of a speech, story, or written work. More formal/literary.
スピーチの冒頭で感謝の言葉を述べた。
In the first part of the speech, I expressed my gratitude.
The opening stage or early phase, often used in games, competitions, or narratives.
ゲームの序盤で大きなミスをした。
I made a big mistake in the first part of the game.
Referring to Part 1 of a multi-part work, such as a book series, film series, or serialized content.
Standard way to say 'Part 1' for structured works. Can be used for books, movies, etc.
このシリーズの第1部はとても面白い。
The first part of this series is very interesting.
The first part of a two-part work. Often used for movies or stories split into two.
その映画は前編と後編に分かれている。
The movie is split into a first part and a second part.
The first volume of a multi-volume book set. Specifically for physical volumes.
The first act or opening number of a show, concert, or theatrical performance.
Used for the first act of a performance, especially in traditional Japanese theater or formal concerts.
コンサートの第一部はクラシック曲だった。
The first part of the concert was classical pieces.
Overture; the introductory music piece. More specific to musical performances.
オペラの序曲が始まった。
The first part of the opera, the overture, began.
前半 (ぜんはん) implies a roughly equal division into halves, while 最初の部分 (さいしょのぶぶん) simply means the beginning portion without implying a 50/50 split. Use 前半 for halves of time or content, and 最初の部分 for the opening segment of any length.
The direct translation 「最初の部分」 is grammatically correct but can sound unnatural in contexts where a specific term like 前半 or 第1部 is expected. Pay attention to whether the 'first part' is a half, an installment, or just the beginning.
この小説の上巻を読み終えた。
I finished reading the first part of this novel.